168 



LAND AND FRESH-WATER SHELLS OF N. A. [PART L 



over the whole parietal wall ; epidermis grayish-yellow, apex rufous ; the 

 striae of growth are very numerous and distinct, crossed by numerous, 

 regular, revolving lines, so deeply impressed as to entirely separate tliem 

 into small sections ; thus the whole surface of the shell is divided into 

 minute, raised parallelograms, separated by the deep longitudinal and 

 ■horizontal furrows. Greatest diam. 22, lesser 19 ; iieight 15 mill. 



Helix iniercisn, W. G. Binxev, Proc. Acad. Nat. Sci. Philad. 1857, 18 ; 



Proc. Bost. Soc. Nat. Hist. VI, 15G (1S57) ; Terr. Moll. IV, 8.— 



Pfeiffer, Mon. Hel. Viv. IV, 349. 

 Helix nickliniana, var., Bisney, Terr. Moll. II, 120 ; III, pi. vi, f. 1 (middle 



figure). 

 Helix crehristriata, Newcomb, Proc. Cal. Acad. Nat. Sci. Ill, 116. 

 Polyviita intercisa, Tkyon, Am. Journ. Conch. II, 319, pi. vi, f. 4 (1867). 

 Arionta crehristriata, Tkyon, /. c. II, 317, pi. vi, f. 2 (1867). 



Fig. 291. 



This species, until quite recently known only by the single 

 specimen in Dr. Binney's collection, supposed 

 to be from Oregon, has recently been described 

 from San Cleniente Island, California, under 

 the name of H. crehrUtriata, by Newcomb, one 

 of whose specimens is here figured. An appa- 

 rently semi-fossil form occurs, with thick shell, 

 heavy, rough growth beyond the peristome, 

 which is made continuous by its ends being 

 joined by a very solid, raised callus. 



Helix cribiistriala. 



292. 



Helix exarata, Pfeiffer. — Shell nmbilicated, depressed-conic, 

 rather solid, malleated and wrinkled, yellowisli, with one chestnut band; 

 spire rather acute, tonic ; whirls seven, equally con- 

 vex, gradually increasing, the last broader, rounded, 

 scarcely falling in front, narrowed around the open, 

 moderate umbilicus ; aperture oblique, broadly 

 hmate ; peristome with a light white thickening, the 

 terminations scarcely converging, the right slightly 

 expanded, the columella triangnlarly dilated above 

 and widening. Greater diam. 30, lesser 25 ; height 

 16 mill. 



Helix exaratn, Pfeiffer, Proc. Zool. Soc. 1857, 108; Mon. Hel. Viv. IV, 



268.— W. G. BiNNEY. Terr. Moll. IV, 12. 

 Agloja exarata, Tkyon, Am. Journ. Conch. II, 312, pi. v, f. 11 (18G7). 



Helix exarata. 



